Malassezia furfur

Synonym: Pityrosporum ovale

Culture of Malassezia furfur on Dixon's agar

Malassezia furfur is characterized by globose, oblong-ellipsoidal to cylindrical yeast cells. Reproduction is by budding on a broad base and from the same site at one pole (unipolar). M. furfur is a lipophilic yeast, therefore in vitro growth must be stimulated by natural oils or other fatty substances. The most common method used is to overlay Sabouraud's dextrose agar containing cycloheximide (actidione) with olive oil or alternatively to use a more specialized media like Dixon's agar which contains glycerol mono-oleate. On such media, colonies are cream to yellowish, smooth or lightly wrinkled, glistening or dull, with the margin being either entire or lobate. Optimum temperature for growth is 35-37C; weak growth occurs at 25C. No fermentation occurs and because of the lipid growth requirements it is not possible to conduct the usual sugar assimilation tests.

Clinical significance:

Malassezia furfur is the causative agent of Pityriasis versicolor and it has recently been implicated as a causative agent of seborrhoeic dermatitis and dandruff. It has also been recovered in blood cultures from neonate and adult patients undergoing lipid replacement therapy. Diagnosis requires special culture media and blood drawn back through the catheter is the preferred specimen. Culture of the catheter tip is also recommended.

Mycosis: Malassezia infections

Further reading:

Guillot, J., E Gueho, M. Jesourd et al. 1996. Identification of Malassezia species. J. Mycol. Med. 6:103-110.